Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Outdoor Air Control, Energyplus EMS If Statement Issue

asked 2015-10-22 11:52:18 -0500

updated 2017-05-17 12:32:15 -0500

I am working on an EMS control to allow me to setback the outdoor air on a pool unit to 50% at night. I have been able to do this using a schedule to override the outdoor air damper with EMS, but then this overrides the economizer ability of the unit. I am trying to get it to go to 50% at night, and then allow it to economize during the day. It seems like the simple if statement in the code below should work, but it makes it so that the unit provides the reduced 50% outdoor air all of the time. I have tried several different ways to do this and cannot get it to work. It seems like this should be an incredibly easy if statement. Any ideas why this isn't working?

Outdoor airflow with the schedule overriding the outdoor air for the day and night time, no economizer. This is what I want at night, but then economizer capability during the day.

image description

Below is the EMS code I used to get the above to work, but with the simple if statement added. If the schedule is less then 1, I want it to override the OA damper, if it is equal to 1, I don't want to override the OA damper.

image description

The outdoor airflow with this code is just at 50% of minimum flow all the time.

image description

Any help would be greatly appreciated.

edit retag flag offensive close merge delete


I would first try adding ELSE to IF (setback_sch <1) statement, and maybe set OA_flow_override_1 to null.

Chandan Sharma gravatar imageChandan Sharma ( 2015-10-22 12:26:22 -0500 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2015-10-22 12:25:08 -0500

Try (or check an EMS example file if I have this syntax wrong):

If setback_sch_1 < 1,
SET oa_flow_override_1 = ...,
SET oa_flow_override_1 = NULL,

edit flag offensive delete link more


Thank you, this worked!

TaylorRoberts gravatar imageTaylorRoberts ( 2015-10-22 13:51:41 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2015-10-22 11:52:18 -0500

Seen: 114 times

Last updated: Oct 22 '15